Law in Australia suggests I can be charged with 'theft by finding' if I don't make a reasonable attempt to identify the owner. This seems to be impossible in this instance...
You can start by posting the address here, so Google indexes it and the owner might respond here.
Do you remember each of your bitcoin addresses down to the last digit? We are talking about those addresses that you rarely use or don't use at all, according to example a paper wallet. It seems to me that it would be more efficient to take a photo of the card from paper wallet, of course, painting over all the text. So at least there will be a chance that the owner will recognize his paper, card or or some other sign if he sees this topic. But I can’t immediately figure out how the owner will confirm his right to this 0.6
BTC if he has neither backups nor access to any information that allows him to confirm.